Direct Z-scheme g-C₃N₄/WO₃ photocatalyst with atomically defined junction for H₂ production

Abstract

Mimicking the natural photosynthesis, artificial Z-scheme photocatalysis enables more efficient utilization of solar energy for sustainable chemical fuel production. Herein, a direct Z-scheme g-C₃N₄/WO₃ photocatalyst with host-guest architecture is rationally designed, demonstrating significantly enhanced activities of photocatalytic H₂ production. Unprecedented atomic-scale imaging of both the in-plane and interlayer structures in g-C₃N₄ revealed the well-defined interfaces in such architecture, where the 2D g-C₃N₄ layers stand vertically on the flat facets of WO₃ nanocuboids. Through both experimental and theoretical investigations, mechanistic insights regarding the direct Z-scheme electron transfer from WO₃ to g-C₃N₄ were obtained. The Z-scheme electron transfer was driven by the internal electric field at the interfacial junction, defined by the covalent W-O-N-(C)₂ interaction. Under simultaneous light excitation, this atomically defined junction induces a rapid electron injection from WO₃ to inhibit the fast recombination kinetics within g-C₃N4 and prolong the charge carrier lifetime of g-C₃N₄, thereby liberating more excited electrons with high reducing power for H₂ production.

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